SB 608 
.T7 S5 
Copy 1 



I. TOBACCO D I S E A S E S. 
II. TOBACCO BREEDING. 



OHIO 

Agricultural Experiment 
Station. 

WOOSTER, OHIO, U. S. A., NOVEMBER, JjMHL. 

BULLETIN 156. 




'vavW 



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EXPERIMENT STATION, Wooster, Ohio. 




ORGANIZATION OP THE 

OHIO AGRICULTURAL EXPERIMENT STATION. 



BOARD OF CONTROL. 



D. D. White, President Casta! i a 

O. E. Bradfute, Secretary Xenia 

D. L. Sampson, Treasurer Cincinnati 

P. A. Derthick Mantua 

Alva Agee Wooster 



STATION STAPP. 

Charles E. Thorne, M. A. S Director 

William J. Green Hr-; i oulturist and Vice Director 

(Superintendent of Orchards, Garden- and Greenhouses.) 

AuGUSriNF D. Selbv, B. Sc Botanist 

(In charg-e of botanical and plan physiological and pathological investigations.) 

C. G. Williams Agriculturist 

(Supei mtendent of Farm.) 

John W. Ames, B. Sc Chemist 

L. H. Goddard Experimentalist 

H. A. Gossard, M. S. . . . Entomologist 

William H. Kramer Bursar 

Clarence W. Waid, B. Sc Assistant Horticulturist 

(In charge of Greenhouses.) 

F. H. Ballou Assistant Horticulturist 

(In charge of Orchards.) 

J. S. Houser, B. S ; Assistant Entomologist 

J. M. Van Hook, A. M Assistant Plant Pathologist 

F. A Welton, B. S Assistant Chemist 

William Holmes Farm Foreman 

Charles A. Patton Meteorological Observer 

Cary Welty Mechanic 

Faye Blayney Mailing Clerk 

M \ry M. Lee Stenographer 

Frank W. Glass Printer 



Edward Mohn Supt. Northeastern Test-farm, Strongsville 

Henpy M. Wachter Supt. Southwestern Test-farm, Germantown 

Lewis Schultz Supt. Southeastern Test-farm, Carpenter 



The Bulletins of this Station are issued at irregular intervals. They are paged 
consecutively and an index is included with the Annual Kep/nt. which constitute 
the final number of each earlv volume. 



BULLETIN 



OF THF 



Ohio Agricultural Experiment Station 



NUMBER 136. NOVEMBER, 1904. 



TOBACCO DISEASES AND TOBACCO BREEDING. 



BY A. D. SELBY. 



I— TOBACCO DISEASES. 

PRELIMINARY AND EXPERIMENTAL STUDIES OF MOSAIC DISEASE, ROOT ROT, 
BED ROT, BROOM RAPE AND CURING HOUSE TROUBLES IN OHIO. 



INTRODUCTION. 

The tobacco' industry in Ohio, though apparently somewhat 
localized, has vital interest for the areas devoted to tobacco growing. 
The writer confesses a personal sympathy with tobacco growers 
bv reason of early experience in the tobacco field. The recent es- 
tablishment at Germantown, Montgomery county, of a Station test 
farm upon which tobacco problems are given especial consideration, 
brings Station officers into closer relations with the tobacco in- 
dustry. Aside from such matters as arose from desultory cor- 
respondence, little attention has been given by the department in 
the past to the study of tobacco diseases. The present publica- 
tion is issued with the double purpose of presenting some matters 
of present value and of securing a closer study of tobacco maladies 
by the growers of this staple. We should be able, in time, to 
increase our present limited and fragmentary knowledge of the 
ti'oubles of the tobacco plant bed, the tobacco field and of the curing 

house. 

87 



88 OHIO EXPERIMENT STATION: BULLETIN 156. & 

TOBACCO DISEASES CLASSIFIED. 

The tobacco plant, in common with many others, suffers from 
any lack of proper nutrition, and the diseases from this cause may 
he varied. We may have unsatisfactory growth and maturity from 
lack of the mineral plant foods or from lack of adequate moisture. 
In the present discussion, however, we shall not attempt to cover 
this line of trou.. lo s; we confine ourselves rather to specific maladies 
which may affect particular plants without touching - others living 
under like external conditions. Here a plant may have abnormal 
color variations in the leaves as by yellow though not dying areas in 
them, at the same time that the adjoining plants of the same 
variety and seed strain are normal in color and healthy in behavior. 
Or a plant may suddenly wilt down and fail to attain full recovery 
and yet another may suffer from dead spots in the leaves. All these 
abnormal features which impair the vigor, productiveness or health- 
fulness of such plants, we term diseases. We shall omit here the 
discussion of insect injuries, though these in a sense come under 
one of the divisions to be considered. The root rot and the wilt are 
parasitic diseases as we shall see later; they are caused by specific 
parasitic organisms. Non-parasitic diseases are such as have no 
specific parasitic organisms constantly associated with them. 

I. NON-PARASITIC DISEASES OF TOBACCO. 
1. THE MOSAIC DISEASE. 

The mosaic disease, or "Frenching", of tobacco, locally known 
in Connecticut as "calico," is one of unusual interest. The diseased 
plants exhibit such a mottled appearance of the leaves, due to the 
alternating areas of darker green and yellowish green in them, as 
to make the appearance of the plants very sti'iking. The leaves 
are veritable mosaics; as such they catch and hold the interest of 
the observer. Certain plants will exhibit these characteristics and 
color markings while others near them have the normal, uniform 
green color. In the tobacco field, as most will recall, plants with 
abnormal color are quite frequent in unfavorable soil situations 
and especially around wet areas. This class of situations is how- 
ever by no means the only one; no particular specifications may be 
made to apply generally in th's respect. The mosaic disease oc- 
curs in practically ail tobacco arer t s of this state and of the United 
States and under favorable soil conditions; indeed the disease is 
general throughout the tobacco growing districts of Europe and 
Asia as well. Along with the mottled, or mosaic ?. pearance of the 
leaves we may have distortions of the leaves doe to the unequal 
rate of expansion in the more healthy and in the diseased areas of 
the leaves. 



TOBACCO DISEASES. 



89 




Plate I — Tobacco leaf showing- Mosaic Disease. 



90 OHIO EXPERIMENT STATION: BULLETIN 156. 

Possibly no other type of plant disease has so long- resisted 
the efforts of investigators to discover the cause producing it. It 
seems now that we must class the mosaic disease of tobacco, the 
yellows of the peach, peach rosette, the mosaic disease of tomatoes 
and the mosaic disease of forcing house cucumbers, which the 
writer has recently investigated at Ashtabula, Ohio, in one and the 
same group of maladies. To discover the actual cause, or causes 
of these diseases has long been the aim of students of plant pathol- 
ogy. In recent years decided progress appears to have been 
made; but as yet the final word is to be said on this matter of cause. 
Mayer 1 early made a careful study of the disease. He showed that 
the disease is transmitted by inoculation and concluded that it must 
be the work of bacteria. In 1898 Beijerinck 2 made a decided contri- 
bution. He showed that the juice of diseased plants, filtered through 
porcelain filters, yet retained the power of producing the disease 
when a small drop of it was injected intoagrowing bud of a healthy 
plant; he also found that diseased tissue kept these infectious 
qualities even after drying and retained its injurious properties in 
the soil during the winter; he further demonstrated that the soil 
around the roots of diseased plants may affect the roots of healthy 
plants. Studies of the disease have been made in our country by 
Sturgis 3 and by Woods'". The last named publication will be of very 
great value to any one who wishes to stud}- the conditions surround- 
ing the production of the mosaic disease in tobacco. Just as in a 
sense Beijerinck was the discoverer of what he called "a living fluid 
contagion'' which he regarded as the cause of the .disease, "Woods 
was able to go further and ascertain the presence of certain enzyms 
in the plants known as oxidizing ferments and named oxidase and 
peroxidase. Both these investigators were able to transmit the dis- 
ease by inoculation of fluid from diseased plants into the young por- 
tions of healthy plants. The difference between the results of the 
one and the other is in the specific designation by Woods of the oxi- 
dizing enzym as the active agent in producing the disease. 

'Mayer, Adolph, Ueber die Mosaikkrankheit des Tabaks. Landw. YerSuch 
Station 32:451-467 pi. I (1886). Review in Jour. Mycol. 7:382-385. 

^Beijerinck, M. W., \'crliainielingen der Koninklijke Akademie van Weten 
schapptn te Amsterdam, Deel 6 No. 5. See also Centb. f. Bakt. Par. &c, 
II, 5:27-33(1899). 

3 Sturgis, W. C, Conn. Exp. Station, Report (1898), 250-254. 

4 Woods, Albert F. , The Destruction of Chlorophyll bv Oxidizing Enzymes. 
Centbl. f. Bakt. Par. &c. II, 5.745 (1899). 

c 'Woods, A. F., ObservaHors on the Mosaic Disease of Tobacco. Bull. Bureau 
of Plant Industry, U. S. D. A. 18:1-24, pi. I-VI. 



TOBACCO DISEASES. 91 

More recently still Hunger 1 " 2 has investigated the mosaic disease 
of Deli (Sumatra) tobacco. Hunger's observations had led him to 
believe that the disease may be communicated by touching first 
diseased then healthy plants, as when the coolies seek for the 
young worms, that is, the larvae which eat the tobacco leaves. He 
planned and carried forward an experiment, using a definite system 
in the matter of touching, and found as a result that a very high 
percentage of the healthy plants, touched directly after a diseased 
plant had been touched in the same tour, became diseased. 
Hunger has contended, as a result of his latest work, that 
not only is the disease infectious by means of the fluid extracts 
from diseased plants, but it is also infectious, we may almost say 
contagious, by this method of touching. 

It has been customary to speak of the mosaic disease as a phys- 
i dogical one, because no parasites in the sense of living or parasitic 
organisms are associated -with it. I have for the present contented 
myself with calling it a non-parasitic disease. 

EXPERIMENTS TO DETERMINE COMMUNICABILITY OF 
MOSAIC DISEASE. 

In 1 ( X>4, under the direction of the writer, Mr. True Houser, 
field assistant of the department, conducted experiments in the 
plots of the test farm at Germantown along the line suggested by 
Hunger's work on Deli tobacco. A few inoculation tests were also 
made, including in all 30 plants. The plants were inoculated in 
different ways; some by insertion of a small fragment from a 
diseased plant in an incision of a healthy plant; others b3 r injection 
of a watery extract of diseased plants into healthy plants. In every 
case the inoculated plants contracted the mosaic disease, the length 
of time after inoculation before appearance of evidence of the dis- 
ease varying from one to two weeks, usually from 9 to 12 days. 

There was no apparent difference between those inoculated 
near the base and those inoculated in the tender portion, although, 
as a rule, only the new growth showed the evidence of the disease. 
In some instances, where rather young leaves were inoculated, the 
disease afterward appeared. In this connection inoculations were 
made of extracts from plants suffering with what is locally known 
as yellow french, wherein the plant has a general yellow aspect. 

'Hunger, F. W. T.. De mozaiek-ziekte bij deli-tabak. Deel I. Verslag 
van de op Deli met betrekking tot de Mozaiek-ziekte genomen proeven in de 
jaren 1901-1902. Med. s' Lands Plantentuin 63, Batavia, 1903. 

*Hunger F. W. T , Die Verbreitung der Mosaik krankheit infolge der Be- 
handlung des Tab.-.ks. Centbl. f. Bakt. Par & c II. 11:405-408. (1904). 

Hri f nsume of Par. 4, Med. s' Lands Plantentuin, 63 (1903) contributed 
, the author. 



92 OHIO EXPERIMENT STATION: BULLETIN 156. 

No result was obtained and no communication of the yellow condition, 
thus confirming' an opinion previously held that this discoloration is 
due to the influence of unfavorable soil conditions. 

Blossoms of various plants were inoculated through the nectar 
by transmission of nectar from diseased plants, as by insect visit- 
ation. A slender brush of horse hair was used for this purpose. 
No evidences of disease were observed as a result of this method. 

MOSAIC DISEASE COMMUNICATED BY TOUCHING. 

The touching - experiments were planned to test the danger of 
communicating the disease through handling first diseased then 
healthy plants, as in the operations of transplanting, worming, 
etc. The touched plants were arranged in sets of eleven plants 
each. In each set were three series of three plants each, marked 
a, b and r, respectively. The plant a of each series was touched 
directly after touching a diseased plant then b and c in succession 
without retouching a diseased plant. Series 1 was touched but 
once; Series 2, twice on succeeding days; and Series 3, three times 
on successive 'days. The same plant was used for c of both Series 
1 and 2, or of Series 2 and 3, making a total of eight plants for the 
three series. The three remaining plants were treated as follows: 
one marked P was touched with considerable pressure (in some 
cases sufficient to break open the tissues of the leaf) after having 
done likewise to a diseased plant; one marked S was touched 
upon the stalk; and the remaining one, marked Z, was touched 
upon the lower leaves. The last three plants mentioned were 
touched twice on succeeding days. 

In all cases, where no' otherwise stated, the touching was 
done on the upper or middle leaves. 

Over 400 plants were touched, but owing to circumstances 
which prevented the collection of sufficient data from part of them 
those with insufficient data have been omitted in the table. After 
the touching, the disease becomes visible, if communicated, only upon 
the new growth and is to be studied as in the cases of inoculation. 

To insure against unintentional touching, the healthy and dis- 
eased plants were wormed and topped at separate times. The 
following table shows in the first part the results obtained upon 
touching the plants as determined upon the dates given, and also 
the increase of disease in the surrounding portions of the field. It 
will be observed from this table that the lowest percentage of 
plants becoming diseased under the \c heading was 35.7 per cent., 
while the highest was 90 per cent., and the average of all the tests, 



TOBACCO DISEASES. 



93 



after the lapse of one month, grave an increase of disease due to this 
cause amounting- to 68.66 per cent. Ag-ainst this increase in the ex- 
periment was an increase of less than 3 per cent in the surrounding- 
plots described in Table I as "not touched." These experiments 
confirm the results obtained by Hung-er and show the necessity of 
great care if the spread of this contag-ious disease is to be checked. 
In the light of these experiments of 1904, it seems highly probable 
that the inferences made in 1903, as to the spread of the disease in 
the handling- of the seedling- plants, or otherwise, during- the field 
practice of that year, are well founded. 

Table I— Showing- the results of observations and experiments as to the spread 

of the mosaic disease in tobacco upon ordinary plants and upon those 

touched with fingers after previous touching of diseased plants. 

PLANTS TOUCHED 



Date of 

touch in''. 



July 26-30 



Manner 
of 

touching-. 



3a 

3b 
3c 
2a 
2b 
la 
lb 

1c 

2-3c 

P 

S 

L 

l-2c 



Total 

No. 

of 

plants. 



Grand total. 



20 
20 
6 
20 
20 
20 
20 
14 
14 
20 
20 
20 



Plants diseased 
by Aug-. 12. 



220 



10 
11 
2 
8 
8 
7 
6 
4 
4 
12 
10 
G 
2 



Per cent. 



96 



55 

33 3 

40 

40 

35 

30 

28.6 

28. C 

GO 

CO 

CO 

333 



Increase of disease 
froai Aug-.12-Aug-.31 



No. 



43.66 



Per cent 



10 


18 


35 


18 


50 


5 


25 


13 


40 


16 


10 


9 


15 


9 


7 1 


5 


42.8 


10 


25 


17 


20 


14 


30 


12 


50 






Total of disease 
up to Aug-. 31. 



No. 



Pi r cent. 



25 



151 



90 

90 

83.3 

65 

80 

45 

45 

35 7 

71 4 

85 

70 

60 

83.3 

68- 6 



PLANTS NOT TOUCHED .* 



6012 



92 



153 



1.28 



286 



4 76 



*A t the beginning- of the i xperiment, 119 plants of the total number, 6,012, or 1 
eased in the areas herein studied 



per cent, were dis 



PREVALENCE OF MOSAIC DISEASE IN SOUTHWESTERN OHIO. 

The writer and Mr. True Houser have studied the disease in 
the Germantown district during- the seasons of 1903 and 1904. 
Taking- some 12 farms in the vicinity of Germantown, Montgomery 
county, including- the Station test farm, there was not a single farm 
on which the mosaic disease did not occur in 1903. The varieties 
grown here are chiefly a cigar leaf filler, known as the "Zimmer" 



94 OHIO EXPERIMENT STATION: BULLETIN 156. 

and the Connecticut seed leaf. The percentage of diseased plants 
varied from less than 1 per cent, to 43.5 per cent, in these scattered 
areas. Upon the Station t» s^ f'irm, where panting was deferred until 
somewhat late, owing - to de.ays incident to plotting- and ditching- the 
tobacco areas, a very curious but withal interesting state of facts 
was found to hold true in 1903. As is common in tobacco fields, the 
plots were of a definite number of rows and the results have been 
calculated dealing with the row as a unit, with the plot as a unit, 
with the fertilized plots and with the unfertilized plots of the area. 
The variations range from to 56 per cent, of diseased plants 
in individual rows of the several plots and f-rom to 38 per 
cent, in the plants of the whole plot. No differences were discov- 
ered as between fertilized and unfertilized plots. To the writer it 
appears that the most striking feature exists in the extremely wide 
variation in the number of diseased plants in different rows of the 
same plot. Stated in its briefest form, we may repeat that the per- 
centage of diseased plants varies from nothing — that is no diseased 
plants — to a little over half (56 per cent ) in individual rows, and oc- 
casionally this range is found within the same plot. Possible 
explanations of this variation in the amount of disease occur to one. 
First, although the plants were set by machine, they were handled 
in removal from the plant bed, and the tendency would probably 
be to gather the plants from a limited area into a single bunch. 
Such bunches might represent a large number of plants diseased 
in the plant bed, despite the intention to reject diseased plants. Sec- 
ond, the apparent contiguous, or more or less contiguous situation 
of the diseased plants in the row may arise from the communica- 
tion of the disease after the manner described by Hunger, as 
above quoted. That there was in these plots late occurrence of 
the disease is shown by the fact that one or more stalks in the 
plot, which had been shorn of the later branches of the panicle 
to preserve a few early blossoms for seed, became subsequently 
diseased. The lateness of this discovery prevented carrying 
out a series of carefully planned observations, as sug-gested by 
the facts already given. In 1904 the seeds from a diseased plant 
of 1903 were planted at Wooster but no disease occured in the 
progeny. 

PREVENTIVE SUGGESTIONS. 

Our preventive suggestions must finally be based on fuller 
knowledge than we now possess. Two suggestions stand out 
prominently in the light of the observations made during the past 
two seasons at Germantown. 



TOBACCO DISEASES. 95 

First, all plants showing- disease in the plant bed should be 
removed. 

Second, it will be found advisable to destroy the diseased plants 
in the field after removal. 

The reason for the first suggestion will be evident and need not 
be further discussed. The basis of the second suggestion is the 
proved communication by touching, first, diseased then healthy 
plants. This amounted to about (>9 per cent, of infection in 1904. 
(See Table I). It is recognized that we must know more of the 
actual losses, both as to quantity and quality, resulting from the 
mosaic disease before we can secure the largest interest on the part 
of the practical tobacco grower. 

Koning 1 has already shown the need for care in topping. In 
this, he reported the result of an experiment on a large scale, in 
1897, in which diseased plants were first topped and directly a great 
number of healthy plants had tops broken by means of the fingers 
infected by the diseased plants; 88 per cent, of these healthy plants 
afterwards became diseased. It is clear therefore that any hand- 
ling of the plants must discriminate between healthy and diseased 
ones. To top, worm and sucker diseased and healthy plants 
separately at different times, with disinfection of the hands before 
passing from the diseased to the healthy, is essential if. we hope to 
limit the spread of the mosaic disease in the field after it once 
appears. 

II. PARASITIC DISEASES OF TOBACCO. 

a. DUE TO PARASITIC FUNGI AND BACTERIA. 

1. ROOT ROT (BLACK ROOT'. 

In 1899 the writer received from Mr. B. W. White, of Neville, 

Clermont county, Ohio, specimen plants of size for resetting, the 

roots of which were attacked by a fungous disease which they had 

designated "black root". This trouble was described as being 

very bad wherever beds were made the second or third year upon 

ground that had been devcted previously to the seed bed. The 

roots of the plants were discolored externally, especially on the 

shin or internode immediately above the earth's surface, often 

accompanied by cracking- and deformation (Fig. 1.). A brief 

examination with the microscope disclosed the constant presence 

of the very characteristic parasitic fungus which we may call the 

tobacco root rot fungus, Thielavia bas : cola Zopf' 2 (Fig. 2). 

l Kpning-, C. J., Die Flecken- oiler Mosaikkrankheit des hollandischen 
Tabaks. Zeitschr. fur Pflauzenkr. 9:b5-80 (1899). 

2 Zopf, Die Pilze. 1890, page 97. 



yb 



OHIO EXPERIMENT STATION: BULLETIN 156. 




From a drawing by "j- M. Van Hook. 

Fig. 1 — Tobacco seedling affected with root rot. 

So far as known to the writer, this is the earliest reported oc- 
currence of this fungus upon the roots of tobacco in America, and of 
this a note was presented before the Botanical Club of the American 
Association for the Advancement of Science, at its Pittsburg - meet- 
ing-. (See Science, new series, 1900. ) Peglion 1 has earlier reported 
upon the root rot of tobacco in Italy, attributed to the same fungus, 
and in America Thaxter has reported its occurrence as a root rot. 
of the violet." Some years ago the writer studied the fungus in 
connection with nematode enlargements upon the roots of the cul- 
tivated Begonia rubra. 3 Latterly, in 1903, similar specimens were 
received from the plant beds of the Station test farm at German- 
town. The Assistant Pathologist, J. M. Van Hook, has recently 
discovered Thielavia producing root-rot of ginseng. In the first 
case mentioned, from Clermont county, the variety of tobacco was 

'Attid. R. Accd. Lincei CCXCIX, V. I-II pp. 32-99. 

"Report Conn. Agr. Exp. Station 13:166-167(1891). 

3 Bulletin Ohio Agricultural Experiment Station, 73:228. (1896) 



TOBACCO DISEASES. 



97 




From a drawing by jf. M. Van Hook 
Fig. 2 -The fungus" of tobacco root rot 



White Burley; the Germantown specimens were of a different vari- 
ety. It is apparent that we have here a parasitic root rot disease 

which, while manifesting itself more 
conspicuously upon the young- 
plants in the plant bed, may be com- 
municated to the larger plants of 
the field should any diseased ones es- 
cape rejection. Aside from the dark 
color due to the reaction .{between the 
parasitic fungus and the host on the dis- 
eased areas, the symptoms of the dis- 
ease are not different from other inju- 
rious root diseases. 

In the matter of preventive measures 
it is clear, from the Clermont county ex- 
perience that, plant beds should be made 
upon new earth each year. Further- 
more, all plants with black root should be 
rejected in resetting. The field develop" 

Thitlavia basicola Zopf. Camera lucida men t of the trouble remains ODetl for 

drawing of the fungus as it occurs upon 

ginseng, tobacco and besronia. a and b g + udy with US. 

conidial forms; c ascospores. All mag- * 

nified 565 diameters. 

2. BED ROT. 

On June 22d, of the present year, the writer observed areas 
in the plant beds of the Germantown test farm, in which the 
plants had damped off, or rotted, as a result of the attacks of some 
specific fungus. The destruction in these areas was strongly 
marked and the diseased plants showed all gradations from fallen 
to lesion-marked stages of the disease. (See Plate II). Specimens 
were collected and photographed and microscopic examinations 
were also made. These show that we have here injury due to the 
fungus Rhizoctonia. It is not possible at this time to state 
any further specific characteristics of the fungus, which does not 
appear to differ essentially from its forms upon other plants, in- 
cluding the potato. 

The source of the Rhizoctonia appears to have been in the soil 
employed or in the added manures. It is evident that we have 
here to deal with a plant bed trouble 'which we have named bed 
rot) of possible serious character, as well as with the root-rot pre- 
viously described. The occurence of this bed rot warns against 
re-seeding in old plant beds. It is quite possible that soil treat- 
ment with formalin, of the strength employed for potato treatment 



98 



OHIO EXPERIMENT STATION: BULLETIN 156. 




From a photograph by j M. Van Hook. 

Plate I -Bed rot of tobacco seedling's, produced by the fungus 

Rhizodonia. 



TOBACCO DISEASES*. (,c > 

might improve conditions, but the chances are much against the* 
successful use of formalin in earth where tender seedlings, like 
those of tobacco, are to be grown and transplanted. It is neces- 
sary in all such cases to reject diseased plants. It does not appear 
that this fungus has been previously investigated in its capacity to 
injure tobacco. Subsequent to the bed studies, or during August, 
plants in the field were observed showing peculiar injury in a rib- 
bon like band extending from root almost to the growing tip. 
These plants tend to wilt down and especially to turn to the side 
with this ribbon lesion. The injury, we have determined, is asso- 
ciated with the bed rot trouble and doubtless results from the 
transplanting of some seedlings marked by this fungus. 

3. DECAY OF TOBACCO SEEDLINGS. 

Behrens 1 has described a wilting and decaying of tobacco seed- 
lings, in which the symptoms consist of a wilting and a slime like 
covering of the wilted parts. With this a dirty green color i.; 
noticed, previous to becoming black. In the later stages a fungus 
may be seen covering the parts, especially the young seed leaves. 
This is identified by Behrens as a species of Alternaria, possibly 
identical with A. tenuis. While it is possible that this disease may 
have been met with in the young seedlings of the plant bed in our 
tobacco districts, it has not been my privilege to examine specimens' 
as yet. Tobacco growers are solicited to send specimens ol the 
young seedlings which may be found drooping, or dying, in the 
plant bed. 

4. THE GRANVILLE TOBACCO WILT. 

Within the past three years a destructive wilt of tobacco has 
been studied in Granville county, North Carolina. The symptoms" 
are described as a drooping of the leaves, which soon become soft 
and flabby, as if suffering from want of water. As a rule, the lower 
leaves droop first, the wilting gradually proceeding from the ground 
upward. Frequently the leaves of one side of the plant succumb 
earlier than those of the other. Often even a single leaf will show 
only one side infected. The wilted leaves soon die, dry up, and 
eventually the whole stalk dies, but remains standing with its dead 
leaves still hanging, and is not to be confounded with the temporary 
wilt due to lack of moisture, excessive heat, etc. At the stage of ear- 

'Behrens. J., Ueber den Schwamm der Tabaksetzlinge. Zeitschr. f. 
Pflanzenkr. 2:327-332, (1892). 

-See Bull. N. C. Agr. Exp. Station 188: (1903). "The Granville Tobacco 
Wilt." 



100 



OHIO EXPERIMENT STATION: BULLETIN 156. 



liest wilting - a section across the stem shows discoloration of the 
woody portion; at more advanced stages the wood is found, either 
"in its internal or outer parts, to be punctured with longitudinal 
black stripes. I have been informed that this disease was ob- 
served in the vicinity of Germantown during 1903. The disease 
differs from that known as "sore shin ,, in the south, in that the 
stem of the wilt-affected plant never topples over from loss of 
roots, as is true in sore shin. 




Fig. 3— Tobacco plant attacked by the Granville, North Carolina, tobacco 
wilt. {From Bulletin 1 88, North Carolina Experiment Station.) 

CAUSES OF THE GRANVILLE TOBACCO WILT. 

Two studies have been published up to this time with respect 
to the cause of the Granville tobacco wilt. The one by Stevens 
and Sackett (North Carolina Agricultural Experiment Station 
Bulletin 188, September, 1903) the other by R. E. McKenney (Bu- 
reau of Plant Industry, Bull. 51, 1903. ) Stevens and Sackett have at- 
tributed the disease to a species of bacterium and have produced the 
disease from cultures of the germ obtained from affected plants. 



' TOBACCO DISEASES. 101 

McKenney, on the other hand, has found the conidia of a fusarium 
in the vessels of diseased plants and attributes the causal relations 
to the fusarium, which also causes wilting- of cotton, cowpea and 
other plants. Whether it may be found upon another investigation 
that one or both of the organisms suggested are the cause of this 
wilt, we apparently have here a parasitic disease of which the cause 
is propagated in the soil and is peculiarly adapted to be destructive 
in case the same soil is planted successively in tobacco. With dis- 
eases of this kind we are sure that crop rotation becomes a neces- 
sity, and soil which produces the disease may be regarded as 
"tobacco sick". The writer would be very much pleased to re- 
ceive information concerning the occurrence of this trouble, or 
of similar troubles, in Ohio tobacco fields. I am indebted to Pro- 
fessor Stevens for the illustration of this wilt (Fig. 3). 

5. LEAF BLIGHT ( FROG EYE). 

Tobacco, in common with most foliage plants, is attacked by 
more than one species of parasitic fungus which produces abnor- 
mal conditions in the leaves. Of this the leaf blight fungus, Cercos- 
pora nicotiance, Ellis & Everhart, is one. This trouble has been de- 
scribed by Sturgis 1 as occurring in North Carolin;;. The writer has 
met with various spotting conditions on tobacco in Ohio and inserts 
this note respecting leaf blight to bring forward observations in 

this line. 

6. white spp:ck and brown spot. 

From North Carolina has come to us the description of another 
disease of tobacco, under the name of white speck, attributed to the 
fungus Macrosporium 'tabacinum Ellis & Everhart 2 . Another 
species of the same genus Macrosporium lonfipes E. & E. is cred- 
ited in the same state as the cause of brown spot. 

7-8. DOWNY AND POWDERY MILDEW. 

In Java, Van Breda de Haan has reported both a powdery and 
downy mildew of tobacco and referred them respectively to Erysiphe 
communis, ( Wallr. ) Lev. and Phytophora nicot/ainr n. sp. In Australia 
these mildews are reported and referred to the same fungi. The 
downy mildew, should it occur with us, may be expected to prove 
destructive. The destructive character of the downy mildew of 
cucumbers as well as the downy mildew or rot fungus of the potato 
may be recalled in this connection. The powdery mildew of the 
pea and of many weeds and other plants, as well as this one of 
tobacco, may be expected to disclose themselves by a whitish covering 
of the growth of the fungus and is much less liable to prove destruc- 
tive. 

'Report Conn. Agr. Exp. Station, 20:273-277 1896. 

2 See Journa: of Mycology 7:134, 1892. 



jf»2 OHIO EXPERIMENT STATION: BULLETIN 156. 

b. DUE TO PARASITIC FLOWERING PLANTS. 
9. BROOM RAPE OF TOBACCO AND HEMP. 

The most of our plant diseases, as we use the term, are pro- 
duced by the attacks of parasitic fungi and bacteria. A few diseases, 
however, are due to parasitic flowering - plants, such as the dodders 
which attack flax, alfalfa, clover and certain wild plants. These dod- 
ders are like other flowering plants, produced from seed -which has 
matured in seed pods or capsules, but they are strongly marked by 
the absence of green foliage; being parasites these have not the ne- 
cessity for chlorophyll to be acted upon by sunlight in elaborating 
food, so the plant does without the green leaves. Broom rapes, which 
are likewise parasitic flowering plants, are analogous in a certain way 
to the dodders but, different in that the broom rape is attached to un- 
derground parts of the host plant — that is to the roots — while the 
dodders become attachedto the parts above the earth. 

The broom rape of tobacco, Orobanche ramosa L. was earlier 
known in Kentucky upon hemp than upon tobacco; it attacks also 
the tomato, rape, cabbage, parsnip, etc., and is known in Japan, 
India, Europe and the United States. It has been described and 
illustrated by Garman*. It is from the last named bulletin by 
Garman that we note the host plants of the different species of 
broom rapes. In this (Bulletin 105) Garman reports the occurrence 
of Orobanche luduvania on tobacco in Davis county, Kentucky. The 
nearest allies, among our common native plants, of this tobacco 
broom rape are the beech drops and the squaw root; also the flowering 
broom rape, which the writer has collected in the vicinity of 
Columbus. Any one who is particularly interested in the broom 
rapes of cultivated plants will do well to consult Professor Gar- 
man's Bulletin 105. The accompanying illustrations, Plates III, 
IV and V will show the manner in which the broom rape occurs in 
Ohio tobacco fields. It has been reported to the writer from a 
small area near Neville, Clermont county, for several years past. 
Specimens were sent to me by Mr. White, in 1901. The photo- 
graphs from which the half tones were made were taken by 
the writer in September of the present year. It will be noted 
that the plants growing under the central tobacco plant of Plate III 
are in bloom, and this broom rape produces seed freely, so that 
it may be dispersed in the seed pod or through theseedsof plants 
like hemp and tobacco. It would appear less likely to become ad- 

*The Hemp Broom Rape of Tobacco. Bull. Ken. Agr. Exp. Sta., 24: 1890; & 
Annual Rpt. Ken. Agr. Exp. Sta., 1890, pp. 57-73, with 8 tiyures.. Also 
Mull. Ken. Ayr. Exp. Sta. 105, Mch. 1903. 



TOBACCO DISEASES. 



103 




i!)4 



diU EXPERIMENT STATION; BULLETIN 15b. 




/ mm a photograph by A. D. Selby . 

Plate IV — Showing tobacco broom rape, Orobanche ramosa, fully developed on 

root of tobacco plant. 



TOBACCO DISEASES. 



105 




106 OHIO EXPERIMENT STATION: BULLETIN 156. 

mixed with tobacco seed, owing - to the manner in which the tobacco 
seed is usually harvested. The area of infection in Ohio is small and 
confined to somewhat low bottoms skirting - the river upon two 
different farms in Washington township, Clermont county. Infec- 
tion here may have come from the transporting of seed by the 
water or it may have come from another source. The clus 
ters of the broom rape often attain a very large size after the har- 
vesting of the tobacco. The amount of seed produced must be 
considerable, so that it will be difficult to get these tracts of land 
entirely free from the broom rape, so long as tobacco growing is 
practiced at intervals. We have no evidence from the small area 
in Ohio as to attack on other plants, but Garman states that in 
Kentucky, infested land may be devoted to grains or grasses with 
safety. Caution is advised with respect to the growing of tobacco 
plants upon soil which is even suspicious. It will be a great draw- 
back to tobacco culture to have other areas of the state so infested 
with rape as are many of the hemp and tobacco lands in Kentucky. 
The fact that it occurs in Ohio on tobacco would serve as a warning 
against its further distribution within the state. 

C. CURING HOUSE TROUBLES OF TOBACCO. 

The tobacco diseases previousl}' discussed relate to the growing 
tobacco plant; other troubles of the curing house, that likewise 
cause loss and impair the quality of tobacco* sometimes occur. 
Those engaged in the curing and subsequent handling of tobacco 
will recall many unfavorable conditions, which tend to affect the 
quality of the crop, aside from its original quality when first cured. 
The fermentations in the process of curing are regarded as essen- 
tial to proper flavor, but unless properly controlled these fermenta- 
tions may produce unfavorable results. 

10. POLE BURN OR POLE ROT. 

This is a disease of the curing house, referred by tobacco 
growers to the effects of warm, damp, foggy weather upon the 
newly hung tobacco. The first symptom is noticed in the neighbor- 
hood of the veins and the midrib of the leaves where moisture is 
abundant; later on the disease may extend. Sturgis has given us a 
very full description in the Connecticut Station report for 1891, 
pages 168-184. The entire contents of the curing barn may be left 
quite worthless as tobacco by the extension of the deadly burn fun- 
gus. The disease may certainly be expected in every tobacco area in 
our country, as it has been known to exist in the past in Connecti- 
cut, Virginia, Kentucky, &c. The too close hanging of the tobacco, 



TOBACCO DISEASES. 107 

with the weather conditions already noted, will be likely to aggra- 
vate the trouble very greatly; while more room an 1 a limited 
amount of artificial heat will be found to be favorable. Insufficient 
ventilation will lead to bad curing-. The actual organisms of the 
decay have been studied by Sturgis, but it is doubtful whether 
these are peculiar to this form of decay as agains.t any other decays 
of vegetable tissues. 

11. STEM ROT. 

When the tobacco stalks are hung up in the curing house the 
leaves wilt and later dry up more or less, while the thick, succulent 
stem dries out but slowly. Under conditions which may prove 
unfavorable to the drying out, or even under average conditions, the 
danger of rotting at the stem is considerable. The stem rot is a 
disease of this character. It begins by white patches of a velvety 
aspect upon the diseased parts, more especially the stem. The 
patches may spread to the veins of the leaf and induce unfavor- 
able results. Sturgis 1 has reported upon this disease and found it 
to be due in Connecticut to a fungus known as Botrytis lougibra- 
chiata, and Behrens 2 agrees with Sturgis except that he regards 
this Botrytis longibrachiata as a form of B. cinerea. 

REMEDIES FOR STEM ROT. 

In the curing house, this is usually remedied by gathering 
the diseased stems and destroying them and by the use of germi- 
cidal sprays in houses where the trouble has been serious. A spray 
consisting of formalin of the strength employed for potato scab 
should be very useful for this purpose and may be scattered 
throughout the building by using an ordinary spray pump, such as 
is employed in orchards. 

_ NOTES ON CURING HOUSE TROUBLE SOLICITED. 

In order to present before tobacco growers some of the con- 
ditions recognized elsewhere, these brief abstracts of curing house 
troubles have been given in this bulletin. More complete notes and 
advices as to the occurrence of curing house troubles will be thank- 
fully received and will meet with response. It will be difficult to 
state just what our peculiar conditions may bring forth in Ohio 
until strict study has been made of these conditions in the curing 
house. 

! Rpt. Conu. Ayr. Exp. Sta. 15:184-186 1891. 

-Trockeue und nasse Faule des Tabaks. ,,Der Dachbrand" (Zeitsehr. f. 
Pflanzenkr. 3:82. 1893. 



108 OHIO EXPERIMENT STATION: BULLETIN 156. 

II. TOBACCO BREEDING. 

PRELIMINARY STATEMENT CONCERNING SELECTION AND CROSSING OF 
TOBACCO IN RELATION TO NEW VARIETIES. 

Since the establishment of the southwestern test farm of this 
Station, through the efforts of the German town Tobacco Growers' 
Association, the various phases of the local tobacco problems have 
been under study. The Department of Plant Physiology and 
Pathology has been requested to take up the question of producing - , 
or -securing new varieties of tobacco for "cigar filler" purposes. 

In the various efforts made during the past two years, the 
results of which are in part indicated on subsequent pages, the 
botanist has been assisted by Mr. True Houser, field assistant of 
the department. The crossing and selection work has been done 
by him under the direction of the writer, who wishes to express 
his obligation to Mr. Houser for efficient assistance. 

It has been stated by many prominent tobacco growers that 
the Zimmer variety, so long grown for locally, cigar filler does 
not meet all requirements, and that, therefore, new varieties should 
be sought. In undertaking an investigation of this character the 
general principles involved are not essentially different from those in 
other lines of plant breeding. The methods may be stated in 
brief to consist either (1) in selection or (2) in crossing followed 
by selection. 

SELECTION-PROCESSES. 

In the method of selection, new strains of established varieties 
are obtained by the choice of individual growing plants of the de- 
sired type, or types. These growing plants may be in special 
gardens or simply in the tobacco field. When suitable types are 
discovered the specimens are protected by bagging from undeter- 
mined cross pollination, and the plant is permitted to ripen a few 
of the earlier seed pods. At the time of bagging the other 
branches of the cluster are clipped off; the bagging must, of course, 
be done previous to the opening of the first blossom. The pro- 
geny from the selections thus made, must subsequently be grown,- 
and the product after curing and fermentation, submitted to the 
necessary tests to determine its quality and special adaptations. 
It is apparent upon reflection, that this method has its limitations 
in regard to the extent of difference between the vaiiet} r grown 
and the desired variety. If the variety already under culture 
possesses most of the desired characteristics, then this method of 
selection will prove well adapted; if, on the other hand, a wide 



TOBACCO DEEDING. 109 

difference exists between the variety grown and the ideal new 
variety, either the process by c:. 1 :t;on alone m is ' c laid aside, or 
a longer time allowed for the breeding- work in order to secure the 
final end sought. The tendency of the variety under culture to 
variation will naturally influence greatly the length of time nec- 
essary to attain the ends in question. However, one serious 
difficulty in tobacco breeding, and this applies at all stages to both 
methods, is the relative immaturity of the tobacco plants at the 
time the seed selection must be made. It is but fair to state in 
this connection that selection alone, if unsatisfactory, must give way 
to other processes of breeding, and that whatever work is done 
must be done under the limitations imposed by the course of 
development run by the plants of the tobacco upon which we work. 

METHOD OF CROSSING AND SELECTION, 

In the second method, namely, that of crossing followed by 
selection, we endeavor to secure the plants for subsequent selec- 
tion by crossing two given varieties. The nature of the tobacco 
flower and its adaptation to self-fertilization, as well as the labor 
necessary to insure cross pollination, must be duly considered. 

While tobacco blossoms are freely visited by birds and insects 
with long bills or probosces, such as the humming birds and the 
hawk moths which lay the eggs of the tobacco worm, thus con- 
tributing to cross pollination, the tobacco blossoms are self fertile 
without insect or other visitation. Their adaptation to insect 
visitation and attraction, through the nectaries of the blossom, are 
but a possible co-operation in the widespread cross pollination se- 
cured in the vegetable kingdom. If, therefore, we wish to cross- 
pollinize, the blossoms must be emasculated by removal of the im- 
mature anthers or pollen sacs, at a time just previous to the fall 
opening of the tobacco oiossom. This period is indicated both by 
the development of the corolla of the flower, including its change of 
color, and by the slight yellowing of the anthers, or pollen sacs, at 
the same time. The emasculated blossoms must then be protected 
from insect visitation, by covering with suitable bags of a hardened 
paper manufactured for this purpose*. Since the anthers are re- 
moved before maturity, at this time the pistil is not mature, 
or receptive to pollen; the receptivity continues for some days 
usually, unless pollination occurs. Ripened and bright yellow s 
from the sort it is desired to cross upon such an emasculated 
pistil, are chosen the next day, or subsequently, and upon the 

*The bag-s used in this work were manufactured by Schmidt, Dusseldorff, 
Germauy, and may be obtained in various sizes. 



110 OHIO EXPERIMENT STATION: BULLETIN 155. 

cautious removal of the bag:, applied to the stigmatic, or sticky 
surface of the pistil of the emasculated blossom. Caution in this 
manipulation is exercised so as to insure only pollination by these 
chosen pollen sacs. Such crossing- does not change the plants upon 
which it is performed, but the cross-fertilized seeds will be in- 
fluenced and grow, when sown, into plants having - certain charac- 
teristics which resulted from the crossing - . Usually these char- 
acteristics have been found to be more or less intermediate, varying 
from those plants showing very close resemblance to the one parent, 
by almost imperceptible gradations into types approaching the other 
parent. In our tobacco work, we have found that in all, more strictly 
intermediate types have prevailed in the progeny; these tj^pes par- 
take very decidedly of the characteristics of both parent varieties. 
The crosses thus far made, have included, more particularly, crosses 
between the large-leafed "Connecticut seed leaf" variety, and the 
slender variety grown in the Miami valley underthe name of "Cuban." 
The illustrations will possibly show how the crosses exhibit the inter- 
mediate characters. Most of the crosses show much larger leaves 
than the Cuban, but with longer internodes than the Connecticut seed 
leaf. The actual qualities of the cured tobacco remain to be 
subsequently determined. 

SELECTION OK CROSSES. 

In the manner above indicated, about 30 crosses were produced 
in 1903. The seed of some of these was lost, but 25 of them were 
grown during the season of 1904. These are recorded by the 
numbers under which the original cross-pollination was entered. 
In this instance, they run from No. 51 to No. 75, inclusive. The 
illustrations will show the variation in part. Another factor will 
be found in the yield of cured leaf, and still another in the quality 
of this leaf. For final application of the results of crosses, the 
favorable, or suitable sorts, must be determined by the processes 
of selection which have been heretofore discussed. Ten out of 
the twenty-live varieties have been rejected, or at least set aside, 
and only fifteen of these are to be planted in 1905. 

While, during 1904, only a single row of each number was grown 
in a plot, in 1905 duplicate 20th acre plots will be grown of each 
selected number, checked by standard plots of the Ziramer an 1 
grown along with plots of the "selection" strains of Zimmer and 
with plots of the Cuban and Connecticut seed leaf. In this manner 
the habits of growth, productiveness and quality of the various 
crosses will be determined in the course of two to five years, ac- 
cording to the amOUut of retesting necessary. 



TOBACCO BREEDING. Ill 

Numbers 53, 54, 55, 58, 59, 61, 63, 64, 68, 69, 70, 71, 72, 74 and 75 
have been selected for plot tests in 1905, while numbers 51, 52, 56, 
57, 60, 62, 65, 66, 67 and 73 have been set aside as of less apparent 
merit. It will thus be seen that the procedures in plant breeding- 
require rather long 1 periods of time; several years are ordinarily 
required in the selection of a suitable type, or variety, from 
crosses or from more or less fixed varieties already grown. It 
always remains to be determined, when a cross is grown, whether 
the plants are uniformly of one type, and if they are not, the sort 
must be grown repeatedly until the type is "fixed." We made 
notes in [the field in 1904 which show that, with the crosses thus far 
studied, the variation among the plants of the rows of the same 
number in 1904, was much less than anticipated. It is expected 
therefore that the fixing of type with the tobacco crosses will be 
less prolonged than in the case of wheat and some other plants. 

This statement of the processes employed and the progress 
made in breeding varieties of tobacco is published at this time, in 
order not only that the members of the legislature who, aided 
in the establishment of this tobacco test farm, and the members 
of the Tobacco Growers' Association, ma}' discover the manner 
in which the Station is carrying out its obligations, but also that 
the general tobacco growing public may know something of the 
operations in this line. Two or more years must yet elapse 
before the results of this tobacco breeding will merit further 
publication. 



112 



OHIO EXPERIMENT STATION: BULLETIN 156. 




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